The Plain of Kadath
On the Last Day, as laid out in the Prophecies, the Armies of the Empire gathered upon the Plain of Kadath. There, they stood in gleaming armor, beneath fluttering banners of etherial silk. There, the Armies of Heaven descended: angels, empyreans, saints and other odder, stranger creatures.
It was on the Plain of Kadath that the Prophecies were derailed. The Legions of Hell did not rise to meet the righteous. The Armies of Heaven and the Empire descended into the Hells to fight the War and the Universe broke.
The Plains of Kadath remain. They stretch from the ruins of the Imperial Capital west, toward the Mountains of Desh.
No one travels the Plain of Kadath if possible. Planar portals open at random throughout the area, offering a brief glimpse into the chaos of the Outer Planes. Occasionally, creatures from other planes emerge from these portals.
Occasionally a benevolent creature will appear on the Plains, a survivor of the extraplanar chaos sweeping the multiverse. If they survive the trek across the Plains and reach either Askir or the Mountains of Desh, they might find welcome and respite in the aarakocra protectorates or the half-dragon controlled imperial capital. Both groups are hungry for news of other worlds.